Lumbar support

ABSTRACT

The lumbar support for a seat backrest according to the invention has a lumbar pad and a toggle linkage to adjust the position of the lumbar pad. Furthermore, it comprises a motor with a spindle and a nut, wherein the motor rotates the spindle to move the nut along the spindle and wherein the nut is coupled to the toggle linkage, which includes an arm member which is pivotably connected to a frame and bears the lumbar pad and a link coupled to the nut and the arm member.

The invention refers to a lumbar support for a seat backrest with a lumbar pad and a toggle linkage to adjust the position of the lumbar pad.

U.S. Pat. No. 4,182,533 discloses a seat backrest having an upholstered cushion portion supported by a rigid frame portion including means to produce a desired supporting contour in the lumbar region of the seat occupant. The contour-producing means includes a lumbar pad resiliently biased pivoted arm members connecting the lumbar pad to the frame through a toggle linkage, and handle means operable from the side of the backrest for adjustably positioning the lumbar pad in a plurality of fixed positions forward of the frame.

DE-A1-29 35 352 relates to a seat backrest with a lumbar pad formed of a flexible plate which is adjustable by a motor with a spindle and a nut, wherein the motor rotates the spindle to move the nut along the spindle and wherein the nut is coupled to the lumbar pad via a rope or cable. A similar construction is known from DE-U1-299 12 855.

EP-A1-1 566 119 discloses a lordosis support including a plate that is adapted to be curved, and an adjusting mechanism for adjusting the curvature of the plate wherein the plate is elastically biased into a curved position and the adjusting mechanism is adapted to reduce the curvature of the plate.

The object of the invention is to improve the adjustment of the lumbar support.

According to the invention, that object is achieved by the features of claim 1.

The lumbar support for a seat backrest according to the invention has a lumbar pad and a toggle linkage to adjust the position of the lumbar pad. Furthermore, it comprises a motor with a spindle and a nut, wherein the motor rotates the spindle to move the nut along the spindle and wherein the nut is coupled to the toggle linkage, which includes an arm member which is pivotably connected to a frame and bears the lumbar pad and a link coupled to the nut and the arm member.

The motor driven lumbar support allows an adjustment of the lumbar pad while the user is sitting in his normal position. In addition, the position of the lumbar pad is not limited to fixed positions.

Further embodiments of the invention are the subject matter of the subordinate claims.

In one embodiment of the invention, the lumbar support comprises a frame for supporting the motor with the spindle and provides a pivot point for the toggle linkage. Preferably, the link is coupled to the arm member in a middle region between the connection of the arm member to the frame and the connection of the lumber pad to the arm member.

In a second embodiment, the spindle is pivotably fixed to the frame with one end and is connected to the arm member via the nut. It is also possible that the toggle linkage has a scissor-type construction.

Furthermore, the lumbar support has a control unit to move the lumbar pad by actuating the motor. According to a preferred embodiment of the invention, the control unit has a time setting device to set a time period for periodically activating the motor to move the nut in order to change the position of the lumbar pad. This function has a very positive influence on the spinal column because the sitting position of the user changes periodically.

Further advantages and embodiments of the invention will be explained by the following description and the drawings.

In the drawings

FIG. 1 shows a side elevation of a seat furniture with a lumbar support,

FIG. 2 shows a three dimensional view of the seat frame and the lumbar support,

FIGS. 3 a and 3 b show a side elevation of the lumbar support in two different positions of the lumbar pad,

FIG. 4 shows a side elevation of the lumbar support of a second embodiment and

FIG. 5 shows a side elevation of the lumbar support of a third embodiment.

FIG. 1 discloses a seat furniture 1 with a seat backrest 2 having a lumbar support 3.

As can be seen in FIGS. 2, 3 a, and 3 b, the lumbar support 3 has a frame 4 which is fixed to a backrest frame 5 of the seat backrest 2. The lumbar support 3 further comprises an actuator with a motor 6, a spindle 7, and a nut 8 wherein the motor rotates the spindle to move the nut along the spindle. Furthermore, the lumbar support has a toggle linkage 9 which comprises an arm member 9 a which is pivotably connected to the frame 4 and a link 9 b coupled to the nut 8 and the arm member 9 a.

The arm member 9 a is coupled to frame 4 at one end and bears a lumbar pad 10 at the other end. The link 9 b is coupled to the arm member 9 a in a middle region between the connection of the arm member to the frame 4 and the connection of the lumbar pad 10 to the arm member.

As can be seen from FIGS. 3 and 3 b, it is possible to change the position of the lumbar pad 10 by moving the nut 8 by rotation of the spindle 7. For actuating the motor 6 a control unit 11 is provided, which may be integrated in the seat furniture 1 (see FIG. 1). However, it is also possible to use a remote control or a control unit which is connected to the motor via a cable.

FIG. 4 discloses a second embodiment of the lumbar support. It differs from the first embodiment in that the spindle 7 is pivotably fixed to frame 4 at pivot point 12 with one end and is connected to the arm member 9′a via nut 8 and a link 9′b. By actuating the motor of spindle 7, the nut will move along the spindle. As a consequence, arm member 9′a with lumbar pad 10 will pivot around pivot point 13.

The toggle linkage 9″ of a third embodiment according to FIG. 5 has a scissor-type construction. It comprises an arm member 9″a consisting of a first link 9.1″a, a second link 9.2″a and a third link 9.3″a and a sliding element 9.4″a. The scissor-type construction also has a link 9″b which is an extension of second link 9.2″a which is pivotably connected to the first link 9.1″a at point 14. Link 9″a is pivotably connected to nut 8 and third link 9.3″a bears lumbar pad 10. By moving the nut 8 along the spindle 7, the third link 9.3″a is guided in sliding element 9.4″a and thereby adjusting lumbar pad 10.

In a preferred embodiment of the invention, the control unit comprises a time setting device 11 a to set a time period for periodically activating the motor to move the nut in order to change the position of the lumbar. Accordingly, it is possible to set a time period of, for instance, two minutes and as a consequence, the position of the lumbar pad will be changed every two minutes a little bit. This has the effect that the position of the user changes every two minutes which has a positive influence on the spinal column of the user. 

1. Lumbar support for a seat backrest with a lumbar pad, a linkage to adjust the position of the lumbar pad and a motor with a spindle and a nut, wherein the motor rotates the spindle to move the nut along the spindle and wherein the nut is coupled to the linkage, characterized in that the linkage is a toggle linkage including an arm member which is pivotably connected to a frame and bears the lumbar pad and a link coupled to the nut and the arm member.
 2. Lumbar support according to claim 1, characterized by a frame for supporting the motor with the spindle and for providing a pivot point for the toggle linkage.
 3. Lumbar support according to claim 1, characterized in that the link is coupled to the arm member in a middle region between the connection of the arm member to the frame and the connection of the lumbar pad to the arm member.
 4. Lumbar support according to claim 1, characterized in that the spindle is pivotably fixed to the frame with one end and is connected to the arm member via the nut.
 5. Lumbar support according to claim 1, characterized in that toggle linkage has a scissor-type construction.
 6. Lumbar support according to claim 1, characterized by a control unit to move the lumbar pad by actuating the motor.
 7. Lumbar support according to claim 4, characterized in that control unit has a time setting device to set at time period for periodically activating the motor to move the nut in order to change the position of the lumbar pad. 